1. Field of the Invention
This invention relates to a pull-type booster for use in brake and/or clutch systems of an automotive vehicle.
2. Prior Art
Generally, the pull-type booster under consideration comprises a hollow body of the interior is divided into a negative pressure chamber and a pressure-variable chamber by a movable member which is movable relative to the hollow body. The negative pressure chamber is connected to a vacuum source such as an intake manifold of an engine while the pressure-variable chamber is selectively caused to communicate with either of the negative pressure chamber and the atmosphere through valve means. The movable member has an inlet for introducing the air into the pressure-variable chamber through a bore therein when the valve means causes the pressure variable chamber to communicate with the atmosphere. As is well known in the art, a boosting force is produced by a pressure differential created between the negative pressure chamber and the pressure-variable chamber. The booster is mounted on a partition wall, dividing the interior of the vehicle body into a passenger room and an engine room, in such a manner that the above-mentioned inlet is disposed within the engine room. When the engine room is cleaned with washing water, the washing water fed in a jet from a water hose or the like is atomized into mist upon impinging on parts in the engine room and an inner wall thereof. The water mist tends to intrude into the interior of the booster through the inlet. Although a filter member is attached to the inlet for arresting dust and the like, it will not prevent the water mist and the jet of water from intruding into the booster.